Why is my object offset from the Bezier curve?
That can happen when the curve and the "tentacle" object do not share the same location. 

Make sure the location (either under the Object tab of the properties window, or the properties region in the 3D view, accessed by N) are the same for both objects, curve and "tentacle."


If both are the same, in edit mode check that the mesh is at the object's origin. As the gif below shows, when the mesh is away from the origin, even both the curve and object show the same location it will still be off the curve.